1. Field of the Invention
The invention relates to an automotive electrical connection box designed to drain water from a lower part of the electrical connection box.
2. Description of the Related Art
An engine compartment of an automotive vehicle is exposed to highly pressurized water during a car wash. Heavy rain and splashes from road surfaces also can direct water into an engine compartment. Thus, it is very difficult to prevent water from entering an electrical connection box in an engine compartment. A completely watertight electrical connection box is complicated and has many parts, thereby increasing production costs. It is also difficult to prevent water from entering along the outer circumferential surface of a wiring harness connected with the electrical connection box.
U.S. Pat. No. 5,159,155 and FIG. 5 herein show an electrical connection box with drainage openings in a bottom wall. With reference to FIG. 5, the electrical connection box has a lower casing 1, and drainage openings 1a are formed in the bottom wall of the lower casing 1. A lower cover 2 is mounted below the lower casing 1 and has a bottom wall that inclines down toward the center. A drainage opening 2a is formed at a bottommost position of the bottom wall. Water that enters the electrical connection box first falls from the drainage openings 1a of the lower casing 1 to the lower cover 2 and is collected. The collected water then drains to the outside through the drainage opening 2a of the lower cover 2.
The drainage openings 1a of the lower casing 1 are at the center of the casing in the electrical connection box of FIG. 5. Thus, water falls down through a part of the electrical connection box that has the internal circuitry, and there is a danger of exposing the internal circuitry to water.
Japanese Unexamined Utility Model Publication No. S63-97328 and FIG. 6 herein disclose another electrical connection box. With reference to FIG. 6, the electrical connection box has a lower casing 3, an upper casing 4 and an internal circuit element 5 therebetween. The lower casing 4 has an upper wall 4a that inclines down from the center towards the opposite lateral edges. An inner surrounding wall 3a stands up from the bottom wall of the lower casing and fits inside a surrounding 4b of the upper casing 4. An outer surrounding wall 3b also stands up from the bottom wall of the lower casing 3 and fits outside the surrounding wall 4b of the upper casing 4. Drainage openings 3c are formed in the bottom wall of the lower casing 3 between the inner and outer surrounding walls 3a and 3b. Thus, water on the upper wall 4a of the upper casing 4 runs down along the slanted surfaces, falls down from the peripheral edge, and drains through the drainage openings 3c at the peripheral edges of the bottom wall of the lower casing 3.
Water runs down from the upper wall of the upper casing 4 to the surrounding wall in the electrical connection box of FIG. 6, and does not pass through the internal circuit element 5. However, the double surrounding wall of the lower casing 3 makes the electrical connection box too large.
The invention was developed in view of the above problems, and an object thereof is to drain water securely and without causing the water to pass an internal circuitry area without enlarging an electrical connection box.